Method for synthesizing high-purity plant-derived cholesterol

Abstract

Disclosed in the present invention is a method for synthesizing high-purity plant-derived cholesterol. By taking plant-derived 21-hydroxy-20-methylpregn-4-en-3-one, also called bisnoralcohol or BA, as a raw material, cholesterol is synthesized by means of steps such as oxidation, Wittig reaction, acetylation, reduction and selective hydrogenation reduction, or the cholesterol is synthesized by means of steps such as oxidation, Wittig reaction, acetylation, reduction, hydroxyl protection, selective hydrogenation reduction, deprotection or hydrolysis, and the purity can reach 99% or above. For the defect that there is cholesterol in a conventional animal source, according to the present invention, a plant-derived raw material, namely BA is used for synthesizing the cholesterol, such that the safety is high, the risk of pathogenic bacteria and virus infection is avoided, the synthesis yield is high, the product purity is good, the environment is friendly, and industrial production is facilitated; moreover, the present invention greatly reduces the impurity level in the product, facilitates the obtaining of high-purity cholesterol, and improves the safety of clinical use.

1 . A method for synthesizing cholesterol with plant-derived 21-hydroxy-20-methylpregn-4-en-3-one BA as raw material, wherein, the method uses BA as raw material to synthesize the cholesterol through oxidation, Wittig reaction, acetylation, reduction and selective hydrogenation reduction; or synthesis of the cholesterol by oxidation, Wittig reaction, acetylation, reduction, hydroxyl protection, selective hydrogenation reduction, deprotection or hydrolysis, specifically comprising the following steps:
 step (a), in the first solvent, the BA shown in formula (1) undergoes oxidation reaction to obtain the compound of formula (2);   step (b), in the second solvent, the compound of formula (2) undergoes Wittig reaction to obtain the compound of formula (3);   step (c), in the third solvent, the compound of formula (3) undergoes acetylation reaction to obtain the compound of formula (4);   step (d), in the fourth solvent, the compound of formula (4) undergoes reduction reaction to obtain the compound of formula (5);   step (e), in the fifth solvent, the compound of formula (5) undergoes selective hydrogenation reduction reaction to obtain cholesterol;   or,   step (f), in the sixth solvent, the compound of formula (5) undergoes hydroxyl protection reaction to obtain the compound of formula (6);   step (g), in the seventh solvent, the compound of formula (6) undergoes selective hydrogenation reduction reaction to obtain the compound of formula (7);   step (h), in the eighth solvent, the compound of formula (7) undergoes deprotection or hydrolysis reaction to obtain cholesterol;   wherein, the reaction process of the said method is as shown in route (A):   
       
         
           
           
               
               
           
         
         wherein, R is selected from ester group, silicon ether group. 
       
     
     
         2 . The method according to  claim 1 , wherein, the ester group is selected from one or more of C2-C10 straight chain ester group, isobutyl ester 
       
         
           
           
               
               
           
         
       
       isopentyl ester 
       
         
           
           
               
               
           
         
       
       phenyl ester 
       
         
           
           
               
               
           
         
       
       p-methoxyphenylcarboxylate 
       
         
           
           
               
               
           
         
         the silicon ether group is selected from one or both of trimethylsilyl ether group 
       
       
         
           
           
               
               
           
         
       
       tert-butyldimethylsilyl ether group 
       
         
           
           
               
               
           
         
       
     
     
         3 . The method according to  claim 1 , wherein, in step (a), the said oxidation reaction is specifically: in the first solvent, BA shown in formula (1), TEMPO, sodium bicarbonate, tetrabutylammonium bromide and oxidizing agent are subjected to oxidation reaction, to obtain the compound of formula (2). 
     
     
         4 . The method according to  claim 3 , wherein, the mol ratio of BA shown in formula (1), TEMPO, sodium bicarbonate, tetrabutylammonium bromide, and oxidizing agent is 1:(0˜1):(0˜20):(0˜1):(1˜5); and/or, the said oxidizing agent is selected from one or more of N-chlorosuccinimide NCS, N-bromosuccinimide NBS, 2-iodoacylbenzoic acid IBX; and/or, the said first solvent is selected from one or more of dichloromethane, tetrahydrofuran, toluene, dimethyl sulfoxide, water; and/or, the temperature of the said oxidation reaction is 0˜30° C.; and/or, the time of the said oxidation reaction is 3˜8 hours. 
     
     
         5 . The method according to  claim 1 , wherein, in step (b), the said Wittig reaction is specifically: 1-halo-3-methylbutane and triphenylphosphine are added into the second solvent, reflux reaction, cooling, suction filtration, to obtain quaternary phosphonium salt; then added the said quaternary phosphonium salt, potassium tert-butoxide into the second solvent, and then added the compound of formula (2), and subjected to Wittig reaction, to obtain the compound of formula (3). 
     
     
         6 . The method according to  claim 5 , wherein, the mol ratio of the compound of formula (2), 1-halo-3-methylbutane, triphenylphosphine, and potassium tert-butoxide is 1:(1˜4):(1˜4):(1˜4); and/or, the said second solvent is selected from one or more of xylene, toluene, benzene, tetrahydrofuran, heptane; and/or, the said 1-halo-3-methylbutane is selected from one or both of 1-chloro-3-methylbutane and 1-bromo-3-methylbutane; and/or, the temperature of the said Wittig reaction is −10˜145° C.; and/or, the time of the said Wittig reaction is 0.5˜24 hours. 
     
     
         7 . The method according to  claim 1 , wherein, in step (c), the said acetylation reaction is specifically: the compound of formula (3), acetyl chloride, acetic anhydride, and alkali are subjected to acetylation reaction in the third solvent to obtain the compound of formula (4). 
     
     
         8 . The method according to  claim 7 , wherein, the molar ratio of the compound of formula (3), acetyl chloride, acetic anhydride, and alkali is 1:(0.5˜62.5):(1˜62.5):(0 ˜6); and/or, the said alkali is selected from one or more of pyridine, triethylamine, DIPEA, DMAP, diisopropylamine; and/or, the said third solvent is selected from acetic anhydride, acetyl chloride, ethyl acetate, dichloromethane; and/or, the temperature of the said acetylation reaction is 40˜110° C.; and/or, the time of the said acetylation reaction is 1˜10 hours. 
     
     
         9 . The method according to  claim 1 , wherein, in step (d), the said reduction reaction is specifically: the compound of formula (4) and the reducing agent are subjected to reduction reaction in the fourth solvent to obtain the compound of formula (5). 
     
     
         10 . The method according to  claim 9 , wherein, the molar ratio of the compound of formula (4) and the reducing agent is 1:(1˜25); and/or, the said fourth solvent is selected from one or more of tetrahydrofuran, ethanol, water, dichloromethane, 2-methyltetrahydrofuran, isopropanol, acetic acid, methyl tert-butyl ether; and/or, the said reducing agent is selected from one or both of NaBH4 and KBH4; and/or, the temperature of the said reduction reaction is 0˜50° C.; and/or, the time of the said reduction reaction is 6˜12 hours. 
     
     
         11 . The method according to  claim 1 , wherein, in step (e), the said selective hydrogenation reduction reaction is specifically: under the action of a catalyst, the compound of formula (5) and reducing agent are subjected to selective hydrogenation reduction reaction in the fifth solvent to obtain cholesterol. 
     
     
         12 . The method according to  claim 11 , wherein, the said reducing agent is selected from H 2 ; and/or, the said catalyst is Raney Ni; and/or, the mass ratio of the compound of formula (5) and the catalyst is 1:(0.05˜5); and/or, the said fifth solvent is selected from one or more of isopropanol, dichloromethane, methanol, 2-methyltetrahydrofuran, tetrahydrofuran, ethanol, water, methyl tert-butyl ether, ethyl acetate, toluene; and/or, the temperature of the said hydrogenation reduction reaction is 0˜60° C.; and/or, the pressure of reducing agent H2 in the hydrogenation reduction reaction is 1˜20 atm; and/or, the time of the said hydrogenation reduction reaction is 6˜10 hours. 
     
     
         13 . The method according to  claim 1 , wherein, in step (f), the said hydroxyl protection reaction is specifically: the compound of formula (5), under the action of an alkali, reacts with the reagent for protecting hydroxyl in the six solvent to obtain the compound of formula (6). 
     
     
         14 . The method according to  claim 13 , wherein, when R is an ester group, the said sixth solvent is selected from one or more of ethyl acetate, dichloromethane, chloroform, DMF, toluene, tetrahydrofuran, 2-methyltetrahydrofuran; and/or, the said alkali is selected from one or both of triethylamine, diisopropyl ethylamine, imidazole, pyridine, DMAP; and/or, the molar ratio of the compound of formula (5), the reagent for protecting hydroxyl, and the alkali is 1:(1˜4):(0.05˜5); and/or, the temperature of the said reaction is 0˜50° C.; and/or, the time of the said hydroxyl group protection reaction is 2˜24 hours;
 when R is a silicon ether group, the said sixth solvent is selected from one or more of DMF, dichloromethane, chloroform, tetrachloromethane; and/or, the said alkali is selected from one or more of triethylamine, diisopropyl ethylamine, imidazole, pyridine, DMAP; and/or, the molar ratio of the compound of formula (5), the reagent for protecting hydroxyl, alkali is 1:(2˜4):(4-8); and/or, the temperature of the said hydroxyl protection reaction is 0˜50° C.; and/or, the time of the said hydroxyl protection reaction is 2˜24 hours. 
 
     
     
         15 . The method according to  claim 1 , wherein, in step (g), the said selective hydrogenation reduction reaction is specifically: under the action of a catalyst, the compound of formula (6), and the reducing agent are subjected to selective hydrogenation reduction reaction in the seventh solvent to obtain the compound of formula (7). 
     
     
         16 . The method according to  claim 15 , wherein, the said reducing agent is selected from H 2 ; and/or, the catalyst is Raney Ni; and/or, the mass ratio of the compound of formula (6) and the catalyst is 1:(0.05˜5); and/or, the said seventh solvent is selected from one or more of 2-methyltetrahydrofuran, tetrahydrofuran, ethyl acetate, toluene, isopropanol; and/or, the temperature of the said hydrogenation reduction reaction is 0˜60° C.; and/or, the pressure of the reducing agent H 2  in the said hydrogenation reduction reaction is 1˜20 atm; and/or, the time of the said hydrogenation reduction reaction is 4˜48 hours. 
     
     
         17 . The method according to  claim 1 , wherein, when R is an ester group, in step (h), the hydrolysis reaction is specifically: under the action of an alkali, the compound of formula (7) is subjected to hydrolysis reaction in the eighth solvent to obtain cholesterol. 
     
     
         18 . The method according to  claim 17 , wherein, the said alkali is selected from one or more of LiOH, KOH, NaOH, t-BuOK, K 2 CO 3 ; and/or, the molar ratio of the compound of formula (7) and alkali is 1:(0.5˜2); and/or, the said eighth solvent is selected from one or both of methanol and ethanol; and/or, the temperature of the said hydrolysis reaction is 10˜75° C.; and/or, the time of the said hydrolysis reaction is 0.3˜12 hours. 
     
     
         19 . The method according to  claim 1 , wherein, when R is a silicon ether group, in step (h), the deprotection reaction is specifically: under the action of a catalyst, the compound of formula (7) is subjected to deprotection reaction in the eighth solvent to obtain cholesterol. 
     
     
         20 . The method according to  claim 19 , wherein, the said catalyst is selected from one or more of tetrabutylammonium fluoride TBAF, tetrabutylammonium fluoride trihydrate TBAF 3H 2 O, boron trifluoride ether, acetic acid, hydrogen chloride in the ethyl acetate solution; and/or, the mass ratio of the compound of formula (7) and the catalyst is 1:(1˜6); and/or, the said eighth solvent is selected from one or both of tetrahydrofuran, water; and/or, the temperature of the said deprotection reaction is 10˜75° C.; and/or, the time of the said deprotection reaction is 2˜48 hours. 
     
     
         21 . Compounds, wherein, the structure of the compounds are shown as formula 6-2(E), 6-3(E), 6-5(E), 6-6(E), 6-2(Z), 6-3(Z), 6-5(Z), 6-6(Z), 6′-1(E), 6′-2(E), 6′-3(E), 6′-4(E), 6′-5(E), 6′-6(E), 6′-1(Z), 6′-2(Z), 6′-3(Z), 6′-4(Z), 6′-5(Z), 6′-6(Z):